The reciprocal approach to the inverse problem of electroencephalography

Forward transfer matrices relating dipole source to surface potentials can be determined via conventional or reciprocal approaches. In numerical simulations with a triangulated boundary-element three-concentric-spheres head model, we compare four inverse EEG solutions: those obtained with conventional and reciprocal transfer matrices, and relating in each case dipole components to potentials at either triangle centroids or triangle vertices. Dipole localization errors are presented in all four cases for varying dipole eccentricity and two different values of skull conductivity. For tangential dipoles, the reciprocal vertex approach performed best overall when considering both skull conductivities. No such clear-cut conclusion could be drawn for radial dipoles.